Hemodynamic profile of SKP-450, a new potassium-channel activator.
Hemodynamic profiles of SKP-450, a newly synthesized potassium-channel activator, were evaluated in conscious hypertensive rats of several types, and in anesthetized and conscious beagle dogs. In freely moving conscious rats, orally administered SKP-450 (0.03-0.3 mg/kg) dose-dependently decreased arterial pressure in spontaneously hypertensive rats (SHRs), renally hypertensive rats (RHRs), DOCA/salt-induced hypertensive rats (DHRs), and normotensive rats (NRs) with a greater potency than lemakalim except in DHRs (ED20 values: SKP-450, 0.021, 0.013, 0.024, and 0.034 mg/kg; lemakalim, 0.107, 0.018, 0.016, and 0.063 mg/kg, respectively). The blood pressure-reducing effects of SKP-450 reached their maximum within 30 min and lasted for approximately 4 h in all rats, and >6 h, particularly, in SHRs. In NRs, pretreatment with glibenclamide (20 mg/kg, i.v.) antagonized the hypotensive effect of SKP-450, whereas propranolol (2 mg/kg, i.v.) antagonized the tachycardiac response of SKP-450 (0.03 mg/kg, i.v.) without affecting its hypotensive response in NRs. In anesthetized beagle dogs, intraduodenally administered SKP-450 (0.003-0.03 mg/kg) dose-relatedly decreased arterial pressure (ED20 value, 0.007 mg/kg) for > or =3 h with its peak effects reached within 15 min and without significant changes in heart rate (HR). Antihypertensive effects of SKP-450 were accompanied by concurrent reduction in total peripheral resistance and dose-dependent increase in cardiac output. Indirect measures of myocardial oxygen demand such as rate-pressure product, tension-time index, and systolic time interval were dose-dependently decreased by SKP-450 without significant change in left ventricular dP/dt(max). SKP-450 significantly increased coronary blood flow and decreased coronary vascular resistance dose-dependently with a rapid onset of action and long duration of >4 h (maximal changes, 276 and 83.7% at 0.03 mg/kg, respectively). In conscious dogs, orally administered SKP-450 (0.03-0.3 mg/kg) produced a dose-related decrease in arterial pressure for > or =3 h, with its peak effects reached within 20 min (ED20 value, 0.030 mg/kg) accompanied by tachycardia. These results suggest that SKP-450 is a potent, orally active peripheral vasodilator activating ATP-sensitive potassium channels.
Lee
B H
BH
Screening and Toxicology Research Center, Korea Research Institute of Chemical Technology, Yusong, Taejon.
Yoo
S E
SE
Shin
H S
HS
D000758:Anesthesia; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D015221:Potassium Channels / Q000819:agonists*; D011760:Pyrrolidinones / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley
D001578:Benzopyrans; D015221:Potassium Channels; D011760:Pyrrolidinones; C096762:KR 30450